I upgrade every year and carry 2 personal iPhones. Right now it is the Space Grey 128 GB iPhone 6 Plus & Silver 128 GB iPhone 6. So, for spetember i will rotate the colors and get the maxed out versions of both the phones!!

I am currently on a 16GB Gold iPhone 6. Haven't ever come up against storage issues, even after a few models with 16GB. I might consider upgrading if it suddenly becomes an issue, though. I hear iOS9 should be a bit more gentle on storage capacity so I'm optimistic.

Otherwise, I'll probably wait until January or February to upgrade if I do. That way, all the chaos around the inevitable bugs and bends and whatever else will be over and I'll really know what I'm getting myself into.